CLEANING NOZZLE AND METHOD FOR CLEANING A DUCT

Abstract: A cleaning nozzle for a device for cleaning ducts has a rear part (1) which can be connected to a pressure-medium source, and a front part (2) which is rotatably mounted on the rear part (1). The nozzle contains a turbine imparting to the front part (2) its rotary motion when pressure medium is supplied to the nozzle. A brush (7) and a friction means (5) are detachably mounted on the front part of the nozzle. In use, the nozzle moves in a helical motion on the inner wall of a duct. The front part (2) rotates about its own axis in such a manner that the relative velocity between the front part (2) and the wall in the contact point therebetween is different from zero. The rotating brush (7) efficiently cleans the inner wall of the duct. If the nozzle loses its grip on the wall, the rotation of the rotating part (2) increases to an idling speed, the friction means (5) expanding such that its diameter becomes greater than that of the brush (7), thus enabling the nozzle to regain its grip on the wall.

Description: CLEANING NOZZLE AND METHOD FOR CLEANING A DUCT The present invention relates to a cleaning nozzle for a device for cleaning a duct, comprising a first part connectible to a pressure-medium source, the cleaning nozzle being adapted to be propelled by the supply of pressure medium, and a second part which is rotatably mounted on the first part and which is adapted to be rotated by the supply of pressure medium, the cleaning nozzle, when placed in the duct and upon supply of pres- sure medium, executing a helical motion along the wall of the duct. The invention also relates to a method for cleaning a duct. The presence of dirt and mould in Ventilation ducts today is a serious problem, resulting in an impaired indoor environment in many dwellings and on many working premises. Contaminated ventilation ducts are also con¬ sidered the cause of infections and allergies. It there¬ fore is highly desirable to be able to develop efficient methods for cleaning ventilation ducts and suitable equipment therefor. Another type of ducts where efficient cleaning tech¬ niques are required, but do not exist today, are water conduits, in which bacteria, fungi, mould and the like constitute a growing problem. From Norwegian Patent No. 41,358 is known a device for flushing sewers and other conduits. This device com¬ prises a pipe which can be connected via a hose to a pressure pump or a water conduit and on which a rotary cap is mounted. Chains are mounted on the cap. When water is fed to the device and flows out of it, the device is propelled in the middle of the pipe by the reaction forces and the cap is rotated about the pipe. The dirt is struck loose from the conduit walls and is flushed away by the water flowing out of the device. From Swedish Patent Application SE 9003183-2 is fur¬ ther known a cleaning device whose nozzle is adapted to be contacted with the inner wall of a conduit and, during the cleaning operation, to move into the conduit while following the inner wall in a helical motion. The device has a front part and a rear part. The front part is rotatably arranged on the rear part, which communicates with a pressure-medium source via a supply pipe. The device further has an annular gap, through which the pressure medium is discharged, the device being propelled by the reaction forces. On the outer side of the device, there is provided a friction ring, by means of which the rotation of the front part can be converted into a motion of the entire cleaning device along the inner wall of the conduit. The conduit is cleaned by means of the pressure medium flowing out through the gap. In many cases, the cleaning effect is however insufficient. This applies especially when the contaminating matter adheres firmly to the walls of the ventilation ducts. In the decontami¬ nation work following a fire, for example, firmly stick¬ ing contaminants pose a major problem. One object of the present invention thus is to pro- vide a cleaning nozzle which is adapted to move along the inner wall of a duct and which is able to clean this in an efficient manner. Another object of the present invention is to pro¬ vide a method for carrying out the cleaning of the inner wall of a duct. These objects are achieved by means of a method and a cleaning nozzle having the features stated in the appended claims. According to the invention, a second part of the cleaning nozzle rotates about its own axis during the helical motion in such a manner that the relative velo¬ city between the wall and the second part is different from zero in the contact point between the wall and the second part. The cleaning effect of the cleaning nozzle is advan¬ tageously provided with the aid of a mechanical cleaning means, preferably a brush, which is mounted on the second part. One problem in this context is that the nozzle, on account of insufficient friction, may lose its grip on the inner wall. To overcome this problem, the nozzle according to the invention is provided with a friction means whose diameter, at rotational speeds below a cer¬ tain limit value, is smaller than or equal to that of the cleaning means, such that it will exert no friction or but a slight friction against the wall, and which at rotational speeds above a certain limit value, expands such that its diameter becomes larger than that of the cleaning means, whereby to grippingly engage the wall. Preferably, the limit value is so selected that the dia¬ meter of the friction means becomes larger than that of the cleaning means at an idling speed, i.e. when the device does not grippingly engage the wall. The friction means according to the invention may of course be used together with cleaning means other than brushes, for example cleaning means using liquid or steam. In one embodiment of the invention, the device comprises a tur- bine which brings about the rotary motion of the rotating part. The turbine operation allows very high rotational speeds and thus enables the cleaning nozzle to move in a helical motion, with the relative velocity in the con¬ tact point between the rotating, second part and the wall being different from zero. An embodiment of the invention will now be describ¬ ed with reference to the accompanying drawing, in which Fig. 1 is a side view of a cleaning nozzle for a device for cleaning ducts, and Fig. 2 is a part-sectional view schematically showing a turbine which may be included in the cleaning nozzle of Fig. 1. As shown in Fig. 1, the cleaning nozzle has a rear part 1 and a front part 2 rotatably mounted on the rear part 1. The rear part has a connecting portion 3 which via a supply pipe (not shown) can be connected to a pressure-medium source (not shown). The pressure medium may consist of compressed air, steam or optionally liquid. Chemicals, such as disinfectants, can be added to the pressure medium in certain applications. The rear part 1 further forms the bottom of a turbine, while the front part 2 forms the turbine housing. The cleaning nozzle has a plurality of openings for discharging pressure medium from the turbine. The design and the number of the openings may vary depending on the application concerned. In the illustrated example, the cleaning nozzle has a primary outlet in the form of an annular gap 4a between the rear part 1 and the front part 2, as well as a secondary outlet in the form of a number of openings 4b along the periphery of the front part 1. As appears from the drawing, the front portion of the front part 2 is conical and a friction means 5 is detachably mounted on this conical portion. The friction means 5 is in the form of a disc and preferably consists of rubber and polyamide. It may, but need not, be rein¬ forced with one or more layers of reinforcing material. The thickness of the disc may, for example, be in the range 1-5.5 mm. Furthermore, the friction means 5 is mounted on the front part 2 by means of a clamping washer 6. A cleaning means in the form of a brush 7 is detach- ably mounted on the washer 6. The brush may consist of different materials depending on the application con¬ cerned. As shown in the drawing, the diameter of the brush 7 exceeds the maximum diameters of the front part 2 and the rear part 1. It may however also be smaller, although this would normally reduce the cleaning effect somewhat. The diameter of the friction means 5 is, when this is inoperative, smaller than or equal to the diameter of the brush 7. When the front part 2 of the nozzle is rotating, the friction means 5 will however expand owing to the centrifugal force, so that its diameter becomes larger than that of the brush 7 when the rotational speed exceeds a certain limit value. The expansion of the fric¬ tion means 5 may, for example, be 25-30% of its diameter. Fig. 2 schematically shows how a turbine in the cleaning nozzle of Fig. 1 may be designed. This Figure shows the rear part 1 and the front part 2, which is shown in cross-section. Between the front part 2 and the rear part 1, there is a space 8, in which extend a plurality of turbine vanes 9 fixed to the front part 2. The longitudinal axes of the turbine vanes 9 may be parallel to the longitudinal axis (axis of rotation) of the turbine. Alternatively, they may be curved, such that the angle in relation to the longitudinal axis varies therealong. As mentioned in the description of Fig. 1, the space 8 has two outlets, namely the primary outlet 4a and the secondary outlet 4b. The channels of the secondary outlet 4b are burred. The rear part 1 further has two sets of openings 10 and 11 on different vertical levels along the periphery of the rear part. One set of openings 10 is located on a level with the secondary outlet 4b while the other set of openings 11 is located closer to the front portion of the rear part 1. When supplying pressure medium via the connection 3 in the rear part 1, pressure medium flows through the two sets of openings 10 and 11, out into the space 8 and via the primary outlet 4a and the secondary outlet 4b out into the duct. The turbine operates in two stages. At low rota¬ tional speeds, the rotation of the front part 2 is pro¬ duced with the aid of pressure medium flowing out through the secondary outlet 4b, while the propulsion is produced substantially with the aid of pressure medium flowing out through the primary outlet 4a. The turbine operation proper does not start until at a higher rotational speed, for example 3,000-4,000 rpm. This turbine design allows a considerable flow of pressure medium, up to at least 6 m^/min, and hence very high rotational speeds. The turbine has been shown together with a mechani¬ cal cleaning means and a friction means. However, it may also be used together with cleaning nozzles of other designs, in which a part of the nozzle is to rotate. It should also be pointed out that other turbine designs are possible within the scope of the invention. For example, the rear part 1 need not have two sets of openings for discharging pressure medium into the space 8. Furthermore, the turbine need not have the secondary outlet 4b, but a primary outlet is sufficient in certain applications. In use, the cleaning nozzle is connected to a supply pipe, in turn connected to a pressure-medium source. The thus-designed cleaning device operates in the following way. The cleaning nozzle is introduced in a duct and the supply of pressure medium is initiated. The front part 2 then starts rotating about its own axis and the nozzle is pressed out against the inner wall of the duct and starts moving in a helical motion along the inner wall. During this helical motion, the front part 2 rotates in such a manner that the relative velocity between the wall and the front part is different from zero in the contact point therebetween, so that contaminants on the inner wall of the duct are efficiently brushed off. The velo¬ city of the advance of the nozzle into the channel is determined by the rate at which the operator moves the supply pipe forwards. The rotational speed in the ope¬ ration of the nozzle may, for example, lie between 5,000 and 20,000 rpm. If the nozzle loses its grip on the wall, the rotational speed increases to an idling speed of e.g. about 30,000 revolutions. The friction means 5 then expands to such an extent that its diameter becomes larger than that of the brush 7, and the nozzle can regain its grip on the wall. The cleaning device can be used in all types of ducts, however preferably in ducts having circular cross- section. The duct diameter may range from about 25 mm to 600 mm. Bends cause no problems. The only limitation actually is that the nozzle should be able to carry the supply pipe. The cleaning nozzle can be used in ducts of a length up to a few hundred metres. In a variant of the embodiment of the invention described above, the brush 7 may be fixedly connected to the rear part 1, between this part and the rotating part 2. This embodiment is especially useful for epoxy-coated ducts and plastic conduits for sewage and water, for which the cleaning effect of a rotary brush would be excessively high. In a further variant, the brush may be integrated in the friction means 5. As mentioned above, the cleaning means need not be a brush, but may have any other mechanical design or rely on ejected liquid or gas for cleaning. In yet another variant, the turbine housing may be stationary and have a shaft on which the brush and/or the friction means are mounted and which is rotated by the turbine.

Claims: CLAIMS 1. A cleaning nozzle for a device for cleaning a duct, comprising a first part (1) connectible to a pres¬ sure-medium source, the cleaning nozzle being adapted to be propelled by the supply of pressure medium, and a second part (2) which is rotatably mounted on the first part (1) and which is adapted to be rotated by the supply of pressure medium, the cleaning nozzle, when placed in the duct and upon supply of pressure medium, executing a helical motion along the wall of the duct, c h a r a c ¬ t e r i s e d in that the second part (2) is adapted, during the helical motion, to rotate about its own axis in such a manner that the relative velocity between the wall and the second part (2) in the contact point there¬ between is different from zero. 2. A cleaning nozzle as claimed in claim 1, c h a r a c t e r i s e d by a mechanical cleaning means (7) and a friction means (5) whose diameter is smaller than or equal to that of the cleaning means (7) when the second part (2) is rotating at a speed below a limit value and whose diameter is larger than that of the cleaning means (7) when the second part (2) is rotating at a speed above said limit value. 3. A cleaning nozzle as claimed in claim 2, c h a r a c t e r i s e d in that the diameter of the cleaning means is at least equal to that of the first part (1) and that of the second part (2). 4. A cleaning nozzle as claimed in claim 2 or 3, c h a r a c t e r i s e d in that the cleaning means (7) comprises brush elements. 5. A cleaning nozzle as claimed in any one of claims 2-4, c h a r a c t e r i s e d in that the cleaning means (7) is fixedly connected to the second part (2) so as to rotate during operation. 6. A cleaning nozzle as claimed in any one of claims 2-4, c h a r a c t e r i s e d in that the cleaning means (7) is fixedly connected to the first part (1). 7. A cleaning nozzle as claimed in any one of claims 2-6, c h a r a c t e r i s e d in that the cleaning means (7) is integrated with the friction means (5). 8. A cleaning nozzle as claimed in any one of claims 2-7, c h a r a c t e r i s e d in that the friction means (5) is in the form of a disc mounted on the second part (2). 9. A cleaning nozzle as claimed in any one of claims 2-8, c h a r a c t e r i s e d in that the friction means (5) is made of a material comprising rubber. 10. A cleaning nozzle as claimed in any one of claims 2-9, c h a r a c t e r i s e d in that the fric¬ tion means (5) is reinforced. 11. A cleaning nozzle as claimed in any one of the preceding claims, c h a r a c t e r i s e d in that the cleaning means (7) and the friction means (5) are detach- ably mounted. 12. A cleaning nozzle as claimed in any one of the preceding claims, c h a r a c t e r i s e d by a turbine means for producing the rotary motion of the second part (2). 13. A cleaning nozzle as claimed in claim 12, c h a r a c t e r i s e d in that the turbine means has a first and a second outlet (4a, 4b) for pressure medium, the first outlet (4b) substantially producing the rotary motion at low speeds. 14. A cleaning nozzle as claimed in claim 12 or 13, c h a r a c t e r i s e d in that the turbine means com¬ prises turbine vanes (9) making an angle with the axis of rotation of the cleaning nozzle that varies along said axis of rotation. 15. A method for cleaning a duct by means of a cleaning nozzle comprising a first part (1) connected to a pressure-medium source, a second part (2) rotat- ably mounted on the first part, the cleaning nozzle being caused to execute a helical motion along the wall of the duct by supplying pressure medium to the cleaning nozzle, c h a r a c t e r i s e d by rotating the second part (2) about its own axis during said helical motion in such a manner that the relative velocity between the wall and the second part in the contact point therebetween is different from zero. 16. A method as claimed in claim 15, c h a r a c - t e r i s e d in that the rotational speed of the second part (2) is at least 5,000 rpm.

Inventors: SUNDFORS JAN, SUNDFORS, JAN
Applicants: MELLANSVERIGES INSTALLATION OC, SUNDFORS JAN, MELLANSVERIGES INSTALLATION OCH MILJOEANALYSER AB, SUNDFORS, JAN
Application year: 1994
Main classification: B08B9
IPC codes: B08B9